Maniraptoran Posted September 15, 2011 Share Posted September 15, 2011 is it true that you can dissolve mudstone matrix with boiling hot water? Link to comment Share on other sites More sharing options...
glacialerratic Posted September 15, 2011 Share Posted September 15, 2011 Haven't tried that yet... Every now and then, I'll find a piece that has silicified fossil bits, and then the matrix can be dissolved with muriatic acid, using very small amounts in a water bath. But, the pieces are small, and the fossils (brachs and coral) are usually broken... Link to comment Share on other sites More sharing options...
bdevey Posted September 15, 2011 Share Posted September 15, 2011 link Link to comment Share on other sites More sharing options...
Maniraptoran Posted September 15, 2011 Author Share Posted September 15, 2011 how big of a tub do you use for the acid bath? Link to comment Share on other sites More sharing options...
Auspex Posted September 15, 2011 Share Posted September 15, 2011 how big of a tub do you use for the acid bath? What acid bath? "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
glacialerratic Posted September 16, 2011 Share Posted September 16, 2011 (edited) :lol: That's funny. How big is your piece? Most of mine have been hand size, so a 2 gal. bucket is plenty big, and no one can fall in. Go very easy on the acid. Water first, drops of acid second, stop when you see a reaction. Let it sit for a day. Repeat. Change the water every now and then. Edited September 16, 2011 by michigantim Link to comment Share on other sites More sharing options...
Auspex Posted September 16, 2011 Share Posted September 16, 2011 I have not seen any discussion here of acid baths; the linked thread talks about mineral spirits vs. hydrogen peroxide. Mudstone is not apt to be affected by acid, anyway, so I don't know how the idea came up. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
ashcraft Posted September 16, 2011 Share Posted September 16, 2011 Unless the mudstone is calcacerous (spelling?????), acid won't have any effect. Unless the mudstone is iron cemented, in which case HCl will dissolve the iron. It is pretty much like anything else, stuff differs so much from location to location, you just have to try it and see. Brent Ashcraft ashcraft, brent allen Link to comment Share on other sites More sharing options...
glacialerratic Posted September 16, 2011 Share Posted September 16, 2011 (edited) Maybe what I call mudstone isn't mudstone... Here's a site with mudstone classification: Conglomerate/Sandstone/Mudstone Ternary Diagram First the rock is disaggregated, usually using acid to dissolve the cement holding the grains together (although DMSO, ultrasound and other methods are also used). Edited September 16, 2011 by michigantim Link to comment Share on other sites More sharing options...
paleoflor Posted September 16, 2011 Share Posted September 16, 2011 In short: depends on the mudstone. And also on how you define the term "mudstone". If you are talking about a lime mudstone, which consists dominantly of carbonate minerals, treatment with (mild) acids should suffice, depending on the amount of matrix which needs to be removed. If however, you refer to a siliciclastic rock that contains a mixture of silt- and clay-sized particles, acid will not always work. It depends on the minerals involved, and, more importantly, on the diagenetic history of the rock. When a siliciclastic rock is cemented with carbonate minerals for example, acids could aid in their removal. Also the type of clay-minerals can make a difference. Disintegrating a rock involves breaking down the bulk into smaller particles. The "boiling-water-method" you refer to accomplishes this feat by bringing the clay minerals (illite, montmorillonite etc.), which have a plate-like structure into suspension. The agitation by the boiling should help lift the clay particles from the rock surface, thereby gradually wearing it down. However, this only will work when the water is able to wet the grain boundaries. When a boundary is wetted, air bubbles due to the boiling can lift off a clay-particle, however, when there is no water present below the particle (i.e. between the particle concerned and the bulk of the rock), this separation is less likely to occur. When swelling clays (smectite, for example) are present in your mudstone, contact with water can completely destroy the rock texture. Swelling clays, as the name suggests, swell when they get in contact with sufficient water. Upon this expansion, they act in a similar fashion to the air bubbles in the boiling water, and help breaking down the rock. We made pieces of Murcia Mudstone (Triassic, Great Britain) which contains considerable amounts of smectite, fall apart without boiling the water last year. These rocks were never buried to significant depths though, which made the strengthening by diagenesis minor. Ultrasonic Baths can also help speed up these processes, as they provide agitation similar to the boiling (actually, air bubbles are formed in the ultrasonic bath, which helps clean stuff in them also). Other mudstones will not do anything appreciable. When illite has been converted to muscovite for example, the rock gains strength and chemical durability beyond what water can wash away on practical timescales. To make a long story short, and to get back to my original answer: it depends on the mudstone. In the Experimental Rock Deformation laboratory where I work we usually try to think in terms of physical and chemical (micro)processes that can help us get the result we want. The first step is to get to know the nature of the material you are working with. If the fossils you wish to retrieve consist of carbonates for example, I'd advise against using any form of acid baths... Cheers, Tim Searching for green in the dark grey. Link to comment Share on other sites More sharing options...
glacialerratic Posted September 17, 2011 Share Posted September 17, 2011 Excellent and informative post, Tim! Link to comment Share on other sites More sharing options...
Maniraptoran Posted September 20, 2011 Author Share Posted September 20, 2011 to michigantim most of the pieces i put in vinegar are usually egg sized to pebble sized, but i always use glass jars with a 1-4 cup capacity. however, the pieces i put in usually stop fizzing after couple of hours, so i suspect i am doing something wrong. to auspex sorry about changing the subject. im from the ADD generation, so my brain will abruptly jump subjects from time to time. i try to make the parameters of my subject more broad next time i post. Link to comment Share on other sites More sharing options...
Maniraptoran Posted September 20, 2011 Author Share Posted September 20, 2011 thanks for all the reading material, but there are still 2 things that i am umclear about 1. how can i tell if a fossil is made of silicate or carbonate? (aside from the acid test) 2. how do i distinguish between calcerous mudstones and non calcerous stones? Link to comment Share on other sites More sharing options...
TqB Posted September 21, 2011 Share Posted September 21, 2011 thanks for all the reading material, but there are still 2 things that i am umclear about 1. how can i tell if a fossil is made of silicate or carbonate? (aside from the acid test) 2. how do i distinguish between calcerous mudstones and non calcerous stones? 1) You could try a hardness test. 2) Acid testing is standard here. Calcite fossils in some mudstones can be very well prepared with potassium hydroxide flakes - place on the matrix, leave for a few hours and the deliquescence breaks up the clay portion which can be washed away. (Wear rubber gloves though, it's very caustic). Tarquin Link to comment Share on other sites More sharing options...
Maniraptoran Posted September 21, 2011 Author Share Posted September 21, 2011 where can i find potassium hydroxide? Link to comment Share on other sites More sharing options...
TqB Posted September 21, 2011 Share Posted September 21, 2011 I got some off eBay (UK) - it's widely used for making biodiesel out of old cooking oil. Tarquin Link to comment Share on other sites More sharing options...
Auspex Posted September 21, 2011 Share Posted September 21, 2011 where can i find potassium hydroxide? My link "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
darrow Posted September 22, 2011 Share Posted September 22, 2011 I sometimes combine the mechanical effects of a heated ultrasonic cleaner with solvent, acid or what ever foul smelling chemical stuff my wife might not want in the house. I place the target item in a nalgene bottle, a ziplock or other suitable sealable container filled with the solvent, seal it and drop it in the water filled ultrasonic cleaner. This accelerates the effects of both and sometimes allows you to reduce necessary soak time if your solvent your wirking with attacks both what you want to remove and what you want to keep. Some experimentation is a good idea and you should have some familiarity with how the stuff your working with normally reacts. Darrow Link to comment Share on other sites More sharing options...
Opisthotriton Posted September 27, 2011 Share Posted September 27, 2011 Maniraptor - The reason your pebbles stop fizzing after a few hours is because household vinegar (acetic acid) is a weak and dilute acid. The reaction slows down as the acid reacts with the limestone and basically gets used up. The reaction is continuing after the fizzing, just more slowly, and after about 24 hours probably isn't doing much anymore. Dump out the liquid and add some fresh vinegar, and watch the fizzing start again! It will take many changes of fresh vinegar to get even a few millimeters into the pebbles, so be patient and buy a lot of vinegar! Or get something stronger... Link to comment Share on other sites More sharing options...
glacialerratic Posted September 27, 2011 Share Posted September 27, 2011 But be careful with the stronger acids... lots of fizzing will will have a negative effect on the fossil. Link to comment Share on other sites More sharing options...
Maniraptoran Posted September 28, 2011 Author Share Posted September 28, 2011 changing the vinegar? darn, i was afraid of that. since im on a budget, is there any way i can extract the calcium and whatnot from the used vinegar so i can reuse it? Link to comment Share on other sites More sharing options...
fossilcrazy Posted September 29, 2011 Share Posted September 29, 2011 When the pH switches don't work; you can try the surfactant method. It will also work in conjunction with Tim's Ultrasonic method. It is a time proven method with one downside. The chemicals are hard to find.Old timers know of "Quaternary O". Those holding a supply are reluctant to part with any. The oldtimers would say it's carcinogenic. I have seen the MSDS and there is no mention of any such thing. Then came along the much improved"Rockquat". The proprietary owner of the formula died leaving very limited amount that got sold fast. Both contain Quartenary Ammonium surfactants. Both Quat-O and Rockquat can be used cold or hot. Boiling supplying much thermo-kinetic energy is heralded to being the fastest method. If you can't locate the materials, a method that can't be done, isn't much of a method. If one were to have a working amount of knowledgeable Chemistry, I am sure the formulations aren't rocket science. Anyone offer a retainer stipend? I'll come out of retirement and compound something better yet. Link to comment Share on other sites More sharing options...
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